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IMPROVEMENT OF EVALUATION METHOD FOR ROCK MASS STRENGTH BY NONLINEAR MULTI-SCALE ANALYSIS

非线性多尺度分析岩体强度评价方法的改进

基本信息

批准号：
17560440
负责人：
KYOYA Takashi
金额：
$ 2.39万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

项目摘要

A strength evaluation method based on the multi-scale analysis for discontinuous rock mass has been improved. Discontinuities in rock mass such as cracks and joints are treated as thin layers and modeled by ordinary solid finite elements, which enables utilization of graphical image of rock mass surface in the analysis. Nonlinear stress-strain relation of crack closing has been carefully observed in a series of compression tests of gypsum mortar specimen, and their nonlinear relation has been formulated in a form of constitutive equation. Cracks are represented by thin layers with the nonlinear constitutive law, instead of complicated contact analysis model, and their nonlinear closing and opening behaviors are expressed by hardening and softening of its stiffness. The nonlinear deformation behavior of rock mass that includes many cracks are therefore appropriately simulated by suing the thin layer model only from graphical image of crack distribution and mechanical properties of intact rocks. In addition, a powerful limit load analysis has also developed by utilizing formulation of the primal-dual optimization and incorporated into the thin layer analysis system. Thus the nonlinear multi-scale analysis system for discontinuous rock mass has been made in a form of prototype. Validation analyses have been done for direct shear test of cracked gypsum mortar specimen and an actual rock mass shearing test in site. Results agreed with measurements fairly well, and revealed the validity of the multi-scale analysis system.

提出了一种基于多尺度分析的非连续岩体强度评价方法。将岩体中的裂隙、节理等不连续面视为薄层，用普通实体有限元进行建模，从而可以利用岩体表面的图形图像进行分析。通过一系列石膏砂浆试件的压缩试验，仔细观察了裂缝闭合的非线性应力-应变关系，并将其非线性关系用本构方程的形式表示出来。裂纹用具有非线性本构律的薄层来表示，而不是用复杂的接触分析模型来表示，裂纹的非线性合开行为用刚度的硬化和软化来表示。因此，仅从完整岩石的裂纹分布和力学特性的图形图像出发，采用薄层模型就能很好地模拟包含许多裂纹的岩体的非线性变形行为。此外，利用原始-对偶优化的公式，并将其纳入薄层分析系统，开发了强大的极限载荷分析。从而以原型的形式建立了非连续岩体非线性多尺度分析系统。对开裂石膏砂浆试件的直剪试验和现场实际岩体剪切试验进行了验证分析。结果与测量值吻合较好，表明了多尺度分析系统的有效性。